A conventional III-nitride heterojunction power semiconductor device includes one III-nitride semiconductor body of one band gap disposed over another III-nitride semiconductor body of another band gap to form a two dimensional electron gas that serves as a conduction channel between the power electrodes of the device. III-nitride heterojunction power semiconductor devices are commercially desirable because of their high band gap and high current carrying capabilities. However, a typical III-nitride power semiconductor device is normally ON. Generally speaking, a normally ON power semiconductor device is less desirable in that it requires additional circuitry to keep its channel open in order to render the same OFF.
It is, therefore, desirable to have a normally off III-nitride power semiconductor device.
Moreover, even in normally ON devices, it may be desirable to set/program the threshold voltage of the device.